1. Field of the Invention
This invention relates to an apparatus for injecting medicaments and to improvements in apparatus suitable for effecting multiple injections.
Automatic injectors are well known. Basically, an automatic injector is a device for enabling an individual to self-administer a dosage of a liquid medicament. An advantage of automatic injectors is that they contain a measured dosage of a liquid medicament in a sealed, sterile condition capable of storage in such condition for an extensive period of non-use, during which period immediate injection of the stored dosage may be accomplished at any time under the most severe emergency conditions. Another advantage of automatic injectors is that the administration of the self-contained dosage of liquid medicament is accomplished without the necessity of the user initially seeing the hypodermic needle through which the medicament is injected or of manually penetrating such a visible needle into the user's own tissue. Instead, an automatic injector includes a releasable stressed spring assembly. This assembly includes a stressed spring, a releasable mechanism for releasably retaining the spring in a stressed storage position and a releasing mechanism for releasing the releasable mechanism in response to a predetermined actuating procedure.
Automatic injectors have heretofore been particularly suited for use under emergency situations. For example, many tens of millions of such automatic injectors have been manufactured and sold containing nerve gas antidotes for use under emergency chemical warfare conditions. Typical units which have been utilized for this purpose are disclosed in U.S. Pat. Nos. 2,832,339, 3,882,863, and U.S. Pat. No. 4,031,893. In addition, units of this type have been proposed for use in administering antiarrhythmic medicaments under emergency conditions relating to heart attack medical situations. Such use has been in conjunction with portable monitors as is evident from the disclosure contained in U.S. Pat. Nos. 3,910,260 and 4,004,577. It has also been proposed to provide other medicaments useful in treating heart attack symptoms, such as clot selective thrombolytic agents (e.g., tPA) and related medicaments. Finally, automatic injectors have been marketed in recent years containing a dosage of epinephrine as an antidote for counteracting severe allergic reactions, as for example, bee stings and the like.
In all of these instances, the emergency use aspect of the automatic injectors is of primary significance.